Plastic cap



April 1966 P. GELBJERG-HANSEN- E'l'AL 3,247,993

' rmsuc CAP Filed April 5, 1964 T l/IIIIIW .36 '34 mvmmkis P5? GELBJEEG-HAA/SEN HOL GEE ME YENDORFF 19 ATTORNEY.

United States Patent s Ciaims. or. 215-41 This invention relates to plastic caps for standard containers of the type provided with a container neck ending in an outwardly projecting annular convex container bead and particularly to such caps adapted to effect sealed clousure of a standard container of said type having contents, which set up excess pressurein the container, and comprising-a top plate, a downwardly extending skirt portion which through a curved transition portion merges into the top plate, and a head portion at the lower end of the skirt portion which head portion comprises an inner clamping bead and an outer supporting bead, whereas the skirt portion is so dimensioned that when the cap is applied to a container neck of the said type the skirt portion is stretched axially as well as circumferenitally. This stretching is necessary for obaining that the cap is able -to seal the container at higher excess pressures therein, for example excess pressures of 12 atm. or more. Further for securing that such caps are, able to be retained on the container in spite of a high inner excess pressure in the container it is necessary that the head portion has a height greater than its thickness.

Normally further by such caps it is to be preferred that the inner face of the skirt portion is provided with a thin filmlike coating of a material softer than the plastic material used for the cap, in which case such a cap is able to secure a proper seal even if the container neck head has an irregular outer surface.

Hitherto known caps of this type are provided with a heavy head portion the supporting head of which has the same height as the clamping head.

When such a cap is applied to,a container neck the head portion has to be dilated in a very high degree since the inner face of the clamping bead must be carried downwards along the outer side of the container neck head which 'has a major outer diameter much greater than the inner diameter of the clamping bead. In case the cap is applied by a pressure being exerted on the upper side of the supporting bead and at a relatively low speed, for example corresponding to the capping of about 5000 containers per hour, normally there will be no difliculties in applying the caps to the containers, but at higher speeds, for example corresponding to the capping of 10,000 to 15,000 containers per hour, too many caps are not correctly applied to the containers owing thereto that the bead portion of these caps have been deformed during the capping process.

An object of the present invention is to provide a cap of the type mentioned which can be applied to containers even at high speed without the caps being deformed unintentionally.

A further object of the invention is to provide a cap of the type mentioned, which has a smaller material consumption than the hitherto known caps of the type mentioned but nevertheless incurs the same advantages as to sealing effect and ability of withstanding high inner pressures in the containers.

Another object of the invention is to provide a cap of the type mentioned which when having once been removed from a container neck by means of a cap remover is able by hand again to be applied to a container neck and also during such reuse being able to seal against high excess pressures in the container and in spite of such 3,247,993 Patented Apr. 26, 196.6

a high excess pressure to be retained on the container neok without risk of it being blown off.

Other obiects and advantages of the present invention will become apparent from this specification, claims and accompanying drawings showing, by way of example only, some embodiments of the plastic cap according to the invention.

In the drawing, wherein like reference numerals indicate like parts:

FIG. 1 is a part sectional view on a large scale of a known plastic cap of the type referred to, on which some embodiments of the invention are shown in broken lines;

FIG. 2 is a part sectional view corresponding to FIG. 1 of a preferred embodiment of the invention;

FIGS. 3 and 4 are corresponding sectional views of the cap shown in FIG. 2 and the upper part of a corresponding bottle neck during and after the capping process respectively; and

FIG. 5 is a part sectional view corresponding to FIG. 1 of a further embodiment of the invention.

FIG. 1 shows with solid lines a bottle cap known per se and comprising a top plate portion 10 which merges into an intermediate portion which includes a curved transition portion 16 and an approximately cylindrical unslit skirt portion 12. The skirt portion 12 continues at its lower end into an elongated continuous annular bottom or bead portion 14. The skirt port-ion 12 has a thickness t'srnaller than the thickness T of the top plate 10. The curved transition portion 16 provides an even transition of thickness between the skirt portion 12 and the top plate 10.

The clamping bead 1-4 comprises an outer supporting =bead subportion 20 arranged outside the outer surface In the following it is provided that the caps are made from an ethylene-propylene co-polymer having a tensile strength of about 250 kg./cm. and a resiliency corresponding to a Youngs modulus of about 056x10 kg] cm.

If the cap dimensioned as appears from FIG. 1 and the outer diameter of the skirt portion 12 is 26.4 mm., the cap will have a weight of about 1.6 g., and when such a cap is applied to a test-neck, that is a bottle neck made from steel and having exactly the standard dimensions of a standard bottle neck of the type shown in FIGS. 3 and 4, the cap will stand an inner excess pressure of 17 to 18 atm. It has to be observed, a cap which has to be used in connection with beer and mineral water must, when applied to a test-neck, stand an inner excess pressure of at least 12 atm. without leaking andwithout being blown off.

For making it easier to apply such a cap to a bottle neck it may seem obvious to provide the clamping head 24 with a conical lower side as indicated with a dotted line 28 in FIG. 1, which conical surface also extends under the supporting head 20. Hereby also some saving of material will be obtained since such a cap will have a weight of about 1.5 g. If such a cap is applied, however, to a test-neck, it has been found that it can resist only an excess pressure of about 5 atm., and, consequently, such a cap is not applicable in practice.

On the contrary, in case the supporting bead subportion ing bead subportion 24 merges with the inner surface 44 of the clamping bead subportion 24, some improvement in the capping process at high speed is perceived. The material saving is very small, but such a cap is able 'on a test-neck to stand an excess pressure of about 17 atm. However, this embodiment is of no interest in practice as appears below.

'An essential improvement in the capping at high speed is obtained, however, in case the supporting head is made still lower, so that its upper surface follows for example the broken line 40 in FIG. 1, merging with the outer face 22 of the skirt portion 12 at a place 42 positioned essentially lower than the transition line 36. Thus in this case the upper surface 40 of the supporting bead 20 merges into the outer surface 22 of the skirt portion 12 at a distance from the lower rim 58 of the bead portion'14 smaller than the distance between said rim and the line 36 at which the upper surface 38 of the clamping bead merges into the inner surface 44 of the supporting head 24, Such a cap has a weight of about 1.5 g. and can on a test-neck stand an excess pressure of about 16 atm.

However, in case simultaneously the cap is modified so that the lower side of the clamping bead 24 is conical as shown by the broken line 28 in FIG. 1, a bottlecap is obtained which without difficulty can be applied to bottles at high capping speed, secure the necessary retaining on the bottle, since this cap can standan excess pressure of about 16 atm., and further an essential material saving is gained since such a cap has a weight of not more than 1.4 g.

As a probable explanation thereof that by the present invention in spite of the weakening of the head portion 14 as a whole an improved application of the cap is obtained without the clamping effect being reduced, the following can be stated:

When a cap as the one shown by solid lines in FIG. 1 is applied to a bottle neck the bead portion 14 will as a whole under axial extension turn somewhat outwards and upwards along the lower end of the skirt portion 12, that is approximately at level with the transition line 34 at which the upper surface 38 of the clamping bead 24 merges into the inner surface 26 of the skirt portion 12, and simultaneously the skirt portion 1 12 is widened whereby the lower part of the-skirt portion will be con cavely curved outwardly. The result is that the inner side of the clamping head 24 will form a relatively great angle to the direction of movement of the cap, and, therefore, danger arises that the clamping bead 24 instead of sliding along the bottle neck bead will be deformed owing to the compressing stresses. On the contrary, provided the supporting head 20' is thus designed that its upper face follows the broken line 49, the bottle neck will influence the bead portion 14 in such a manner that instead of under radial widening to turn outwards and upwards, still under radial widening the bead portion 14 will turn inwards with its lower end owing thereto that the bottle neck influences the inner side of the clamping bead 24, and the inwards swinging is made possible owing to the relatively short distance between the place 42 and the upper surface 38 of the clamping head 24. Simultaneously the skirt portion 12 will, instead of with its lower end under radial widening to curve concavely outwards, with its lower end curve inwardly so that during the capping process the lower part of the skirt portion 12 is curved approximately corresponding to the curved form it adapts when the cap is applied to the bottle neck. The intermediate portion 16, 12 is thus upon mounting onto the bottle 60 (FIG. 3) being stretched longitudinally and circumferentially and therefore in all directions and is thereby molded sealingly in fitted position to the bottle bead. The inwards curving of the bead portion 14 involves that the resistance against the introduction of the bottle neck into the cap is reduced.

, This effect is still more pronounced when further the lower side of the clamping bead 24 is made conical, for

example corresponding to the broken line 28. In this case the clamping head 24 will during the applying of the cap to the bottle neck be brought to curve inwards in a still greater degree than the supporting bead 20 since owing to the short distance between the place 42 and the line 28 the supporting bead 20 will be able to swing somewhat outwards relative to the clamping bead 24. Owing thereto the forces necessary for providing the stated swinging of the head portion 14 and thereby the deformation stresses influencing the clamping bead 24 will be further reduced.

When the bottle cap is applied to the bottle neck the clamping bead 24 will penetrate into the groove below the bottle .neck bead and the transition line 34 will adopt a position approximately corresponding to the transition between the outer and lower side of the bottle neck bead.

Simultaneously the supporting head 20 will tend to contract to adopt its original size, and thereby it generates a The clamping bead 24 will cause an inwards directed shrinking. pressure too,

radially inwards directed pressure.

but it will also be influenced by relatively strong axial forces in the longitudinal direction of the skirt portion 12,

'which last said forces tend to turn the clamping bead 24 r outwards. The said axial forces acting on the upper part of the head portion 14 will not, however, or only in a slight degree, influence the supporting head 20. This will tend to move inward-s thereby turning relative to the clamping bead 24 where the bead portion 14 is thinnest, that is near the transition 42. Consequently, the supporting head 14 will influence or bias the clamping head 24 and try to turn of the upper part of the bead portion 14 will counteract the inwards turning of the lower part of the supporting head 20.

A preferred embodiment of a cap according to the present invention is shown in FIGS. 2 to 4. In this embodiment the top plate 10, the skirt portion 12, the curved transition portion 16, the upper face 38 of the clamping bead 24, and, thereby, the transition lines 34 and 36 are formed, dimensioned and arranged in the same manner as the corresponding portions of the known cap shown in solid lines in FIG. 1. The inner face 44 of the clamping bead 24 has a relatively small height and merges through a comparatively sharp transition 46 into a conical lower face 48 simultaneously forming the inner side of the lower part of the supporting bead 20. The supporting head 20 a is provided with an upper face 50 which through a concave curvature 52 having a radius of curvature at least equal to the thickness 2 of the skirt portion 12, preferably about 1.5 X t, merges into the downwards extension of the outer surface 22 of the skirt portion at a transition line 54 having a distance from the lower rim 58 of the bead porlower side of the supporting bead forms the lower rim 58 i of the beadportion 14 and is, as norm-ally is the case, horizontal, provided the axis of the cap is vertical.

Compared with the cap shown in solid lines in FIG. 1, the cap shown in'FIG.,2 implies a great material saving since it has a weight of only 1.3 g. so that a material saving of 20% is gained. Nevertheless caps as the one shown in FIG. 2 are able on test-necks to stand an excess pres sure of about 16 atm., that is only 1 atmless thanthe;

known cap shown in FIG. 1. I

FIG. 3 shows the deformation of the cap shown in FIG.

2 during its applying to a bottle neck $0. In FIG. 3 the cap is shown in the position it takes up when the widening of the head portion 14 is greatest. By comparing FIGS. 2 and 3 it appears that the cap must take up the position shown in FIG. 3, and also that by the shape shown in FIG. 3 the cap will olfer only a slight resistance against its application when the cap is applied to the bottle neck by means of a device providing a vertical pressure on the upper side 50 of the supporting bead 29.

FIG. 4 shows the cap of FIG. 2 applied to the bottle neck 60. From this figure it appears that the supporting bead must exert an inwards directed bending moment on the clamping bead 24. It also appears how, owing to the deformation, the lower side 58 of the bead portion 14 gets comical tapered inwards and upwards causing that the inner tongue of a normal bottle opener easily may slide in below the lower side 58 and grasp this side. From this figure also appears why the radius of curvature of the curved portion 52 must be comparatively great. In case the transition between the upper side 50 of the supporting head and the outer side 22 of the skirt portion was sharp, the supporting bead 20 would mainly when acted upon by an opener be swung outwardly about the transition 54 without directly to act upon the clamping bead 24, so that only the supporting effect of the supporting bead subportion 2% on the clamping bead subportion 24 would be reduced. In practice the pressure within a bottle containing beer or mineral water will be essentially lower than the pressure which may arise within the bottle, for example during pasteurization or when the bottle is shaken, and, therefore, a reduction of the effect of the supporting bead on the clamping bead will normally not be sufi'lcient for removing the cap. In case, however, the curved portion 52 has a comparatively great radius of curvature, as shown, the swinging of the supporting bead by means of an opener will also incur an outwards swinging of the clamping bead so that the cap is easy to remove when it is wanted. At the cap shown in FIG. 1, however, the corresponding transition ought to have a very small radius of curvature since otherwise by this embodiment the axial pull forces in the 'skirt portion 12 will tend to swing the supporting bead outwards and thereby to reduce its effect on the clamping bead. As shown in FIGURE 4, the intermediate portion 16, 12 is sealingly held against the bottle head by clamping bead subportion 24 having an embracing surface 38 which surroundingly embraces the underside of the bottle closure bead.

A special embodiment of the cap according to the invention is shown in FIG. 5. The cap shown in FIG 5 differs from the cap shown in FIG. 2 only by the shape of the supporting bead which by the embodiment shown in FIG. 5 outwardly is limited only by a conical surface 62 which merges with the continuation of the outer surface of the skirt portion 12 at the transition 54 situated opposite the inner surface 44 of the clamping bead 24 on a level between the levels defined by the transition lines 36 and 46. By this embodiment a still greater material saving is gained, since such a cap has a weight of only about 1.2 g. This cap may be applied to the bottle neck by means of a capping device of the same type which is used for capping metallic caps of the crown type and comprising an inwardly conical piston. The comparatively weak dimensioned supporting head 21 will by this embodiment have the same effect as explained above, but this eflect will in this embodiment be further assisted thereby that during the capping process the supporting head 20 will receive a a permanent deformation and be pressed into the groove below the bottle neck head so thatwhen the cap is applied to the bottle neck the outer surface 62 of the supporting head will take up a nearly vertical position. The bending moment exerted by the supporting bead 20 on the clamping bead 24 together therewith that owing to the permanent deformation the material of the supporting bead grows stiffer results therein that the cap shown in FIG. 5 is able on a test-neck to stand an excess pressure of about 12 atm. which is acceptable. Owing to its small material consumption the cap shown in FIG. 5 is cheap to produce, but at least when made by a usable plastic material of the types hitherto known owing to the permanent deformation of the supporting bead when the cap is applied to a bottle neck the supporting bead will get another appearance than the other parts of the cap. In case the plastic material is coloredthe supporting head 20 will be lighter than the other parts of the cap with a white or grey tinge, and in case the plastic material is colorless or white the supporting head will be grey. Therefore, for the time being a cap as shown in FIG. 5 will possibly be of no practical interest, but it is possible that new plastic materials or new dye stuffs for plastic materials will appear making it possible to avoid the changing in appearance of the deformed supporting head 20.

As appears from the above, compared with known plastic caps, for example caps of the type shown in FIG. 1, the cap according to the invention implies several advantages such as a smaller weight and thereby a smaller 7 material consumption, a secure application even by great speed, and an easy removing by means of the hitherto normally used bottle openers whereas the known plastic caps demand a specially formed opener. Apart herefrom, however the new cap has shown to possess a quality implying an essential advantage at least for the users of bottles closed by such caps. It appears that even though a cap as the one shown in FIG. 2 when unused cannot be applied to a bottle neck by hand, when first once having been removed by means of a cap remover it can be reapplied to a bottle neck by hand and thus reused as a closure for the bottle, for example in case only a portion of its contents having been used. However, even after reuse the cap cannot be removed from the bottle by hand, but a cap remover is necessary. Further it appears that for example the cap shown in FIG. 2 even after having been used 8 to 10 times is able on a test-neck to stand an excess pressure of about 10 atm. and also to secure tightness. This effect of the invention is surprising and diflicult to explain. Possibly it is owing thereto that by the first removal by means of a cap remover a local overload of the bead portion 14 is brought about so that a narrow axial zone of the bead portion becomes easier extensible than the further parts of the head portion whereby the possibility of applying the cap by hand is obtained whereas the not influenced parts of the head portion keep their clamping properties. As the skirt portion '12 is not acted upon during the cap removing the scaling properties of the cap are not influenced by the removing of the cap.

It is to be understood that the embodiments of the invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the shape, size and arrangement of parts may be resorted to Without departing from the spirit of the invention or the scope of the claims. Thus for example the distancebetween the rim 58 and the place 54 whet the supporting bead merges with the extension of the outer surface of the skirt portion 12 may vary within great limits although as appears from the foregoing it has to be smaller than the distance between the rim 58 and the transition line 36. Preferably the distance between the rim 58 and said place 54 is between 0.5 and 0.75 times the distance between the rim 58 and the transition line 36.

We claim:

1. A container closure adapted to be fitted upon a container closure head at the open top by stretching comprising a plastic continuum, said continuum being shaped into portions to provide means as follows viewing the closure placed in operative position atop a container:

(a) a top portion providing a first means to close the top of said container;

(b) an intermediate portion providing a second means as a skirt depending at one of its ends from said first means, said second means normally prior to .mounting having a major inner diar'rietefland other dimensions, smaller than the major diameter and respective other dimensions of the container bead and upon mounting onto the container being stretched longitudinally and circumferentially and therefore in all directions to thereby be molded sealingly in fitted position to the container bead; (c) an elongated continuous annular bottom portion subtended at the other end of said secondmeans providing a third means as a bead shaped and adapted to provide A (1) a clamping bead subportion, and (2) a supporting bead subportion said clamping bead subportion extending inwardly relative to the inner surface of said skirt providing a clamp fitting against and having an embracing surface surroundingly embracing the underside of the containerclosure bead thereby maintaining stretched said second means,

said supporting bead subportion extending outwardly relative to the outer surface of said skirt and being located below the embracing surface of said clamping bead subportion and being stretched circumferentially generating a shrinkage force,

said third means bead at its lower end exerting said shrinking force biasing inwardly and upwardly the upper section of said clamping bead subportion having said embracing surface.

2. A container closure, according to claim 1, wherein the supporting bead subportion merges with said intermediate portion at the outer surface thereof at a distance from the bottom of said supporting bead subportion ranging from about 0.5 to about 0.75 of the distance between said bottom of said supporting bead subportion and said embracing surface.

3.. The combination with a container of the type having a neck ending in an outwardly projecting annular convex bead of a container closure adapted to be fitted upon said bead at the open top by stretching to eiiect sealed closure of said container having contents setting up an excess pressure; said container closure comprising a plastic continuum, said continuum being shaped into portions to provide means as follows viewing the closure placed in operative position atop a container:

(a) a top portion providing a first means to close the top of said container;

(b) an intermediate portion providing a second means as a skirt depending at one of its ends from said first means, said second means normally prior to mounting having a major inner diameter and other dimensions smaller than the major diameter and respective other dimensions of the container bead and upon mounting onto the container being stretched longitudinally and circumferentially and'therefore in all directions to thereby be molded sealingly in fitted position to the container bead;

(c) an elongated continuous annular bottom portion subtended at the other end of said second means providing a third means as a bead shaped and adapted l to provide (1) a clamping bead subportion, and (2) a supporting bead subportion said clamping bead subportion extending inwardly relative to the inner surface of said 1 skirt providing a clamp fitting against and having an embracing surface surroundingly embracing the underside of the container closure bead thereby maintaining stretched 1 said second means,

said supporting head subportion extending outwardly relative to the outer surface'of said skirt and being located below the embracing surface of said clamping bead sub-, 1 portion and being stretched circumferenferentially generating a shrinking force, said third means bead at its lower end exerting said shrinking force biasing inwardly and upwardly the upper section of said clamping bead subportion having said embracing surface.

4. A container closure according to claim 1 having 1' 0n the inner surface of said intermediate portion a thin film coating of a material softer than the material of said lastic continuum.

. 5. A container closure according to claim 3 having on the inner surface of said intermediate portion a thin film coating of a material softer than the material of said plastic continuum, whereby said closure retains its sealing capacity when said container head has been injured prior to closure.

6. A closure according to claim 1 wherein the plastic continuum is selected from a polymer or copolymer of ethylene and propylene.

7. A plastic cap as defined in claim 1; said supporting bead subportion being provided with a conical outer face having its major diameter at the lower end thereof.

8. A plastic cap as defined in claim 1; said supporting bead subportion merging into said intermediate portion concavely at a radius of external curvature larger than the thickness of said intermediate portion.

References Cited by the Examiner FRANKLIN T. GARRETT, Primary Examiner. 

1. A CONTAINER CLOSURE ADAPTED TO BE FITTED UPON A CONTAINER CLOSURE BEAD AT THE OPEN TOP BY STRETCHING COMPRISING A PLASTIC CONTINUUM, SAID CONTINUUM BEING SHAPED INTO PORTIONS TO PROVIDE MEANS AS FOLLOWS VIEWING THE CLOSURE PLACED IN OPERATIVE POSITION ATOP A CONTAINER: (A) A TOP PORTION PROVIDING A FIRST MEANS TO CLOSE THE TOP PORTION PROVIDING A FIRST MEANS TO CLOSE THE (B) AN INTERMEDIATE PORTION PROVIDING A SECOND MEANS AS A SKIRT DEPENDING AT ONE OF ITS ENDS FROM SAID FIRST MEANS, SAID SECOND MEANS NORMALLY PRIOR TO MOUNTING HAVING A MAJOR INNER DIAMETER, AND OTHER DIMENSIONS, SMALLER THAN THE MAJOR DIAMETER AND RESPECTIVE OTHER DIMENSIONS OF THE CONTAINER HEAD AND UPON MOUNTING ONTO THE CONTAINER BEING STRETCHED LONGITUDINALLY AND CIRCUMFERENTIALLY AND THEREFORE IN ALL DIRECTIONS TO THEREBY BE MOLDED SEALINGLY IN FITTED POSITION TO THE CONTAINER BEAD; (C) AN ELONGATED CONTINUOUS ANNULAR BOTTOM PORTION SUBTENDED AT THE OTHER END OF SAID SECOND MEANS PROVIDING A THIRD MEANS AS A BEAD SHAPED AND ADAPTED TO PROVIDE (1) A CLAMPING BEAD SUBPORTION, AND (2) A SUPPORTING BEAD SUBPORTION SAID CLAMPING BEAD SUBPORTION EXTENDING INWARDLY RELATIVE TO THE INNER SURFACE OF SAID SKIRT PROVIDING A CLAMP FITTING AGAINST AND HAVING AN EMBRACING SURFACE SURROUNDINGLY EMBRACING THE UNDERSIDE OF THE CONTAINER CLOSURE BEAD THEREBY MAINTAINING STRETCHED SAID SECOND MEANS, SAID SUPPORTING BEAD SUBPORTION EXTENDING OUTWARDLY RELATIVE TO THE OUTER SURFACE OF SAID SKIRT AND BEING LOCATED BELOW THE EMBRACING SURFACE OF SAID CLAMPING BEAD SUBPORTION AND BEING STRETCHED CIRCUMFERENTIALLY GENERATING A SHRINKAGE FORCE, SAID THIRD MEANS BEAD AT ITS LOWER END EXERTING SAID SHRINKING FORCE BIASING INWARDLY AND UPWARDLY THE UPPER SECTION OF SAID CLAMPING BEAD SUBPORTION HAVING SAID EMBRACING SURFACE. 